Alan Is a Single Taxpayer with a Gross Income of $88,000

Alan is a single taxpayer with a gross income of $88,000, a taxable income of $66,000, and an income tax liability of $12,356. Josh also has $8,000 of tax-exempt interest income. What are Alan's marginal, average, and effective tax rates?

A) 25% marginal; 16.7% average; 18.7% effective.
B) 28% marginal; 15.9% average; 21.5% effective.
C) 28% marginal; 16.7% average; 21.5% effective.
D) 25% marginal; 18.7% average; 16.7% effective.